In the example of illuminated floats being used with fishing nets, such as purse seines, towing nets, stationary nets, gill nets, longlines, nets used to define fish preserve or culture and so on. In general, floats are fastened to predetermined positions of the fishing nets in order to identify the positions of the fishing nets and to maintain the fishing nets in water in a desired shape.
In order to enable the visual perception of such floats at night, reflecting elements are attached to the surfaces of the floats or storage type fluorescent materials are coated over the surfaces of the floats.
However, the floats with reflecting elements attached to the surfaces thereof have the following problems.
That is, the reflecting elements are only bonded to the surfaces of the floats. They tend to be easily separated from the floats when the floats are thrown into the water and when they collide against the hull of the ship vessels as they are retrieved on the ships or against drifts. They are also separated due to friction. Furthermore, in order to visually perceive such floats, light sources must be provided in order to emit the light rays which in turn are reflected by the reflecting elements. In addition, the visual perception distance is limited by the capacity or intensity of the light sources. In addition, when the floats move or the ships pitch, roll and rock, it becomes difficult to correctly strike the light rays against the reflecting elements so that it becomes very difficult to find the floats with the reflecting elements.
Meanwhile, the storage-fluorescent material coated floats also have some problems as described below.
That is, since the fluorescent materials are only coated over the surfaces of the floats, they also tend to be separated as in the case of the floats with the reflecting elements. Furthermore, in order to store the energy into the fluorescent materials, the light sources are also needed. The storage batteries used were not efficient enough to store the proper amount of electrical energy needed to energize the light-emitting element. In addition, their light-emission time is short, and the maximum luminance from the light-emitting element is so low, the distance at which floats can be perceived is extremely limited. Moreover, their luminance decreases as time elapses so that it becomes difficult to see them. The luminance of a fluorescent material is in a general in proportion to the intensity of light emitted from a light source so that when the light rays are emitted from a distance spaced by some distance from a float in order to make the luminance of the floats perceivable, a light source having a relatively high light-emitting capacity is needed. As a result, the cost is increased and a light source used in increased in size and weight so that relatively large space for installation of a light source must be provided on ship.